Cold-formed steel storage rack
A selective pallet rack of cold-formed upright frames and pallet beams: the beams with the connector's rotational stiffness, the connectors, the perforated uprights, the frame bracing, seismic forces in the down-aisle and cross-aisle directions, overturning and the base plate. The governing standard is ANSI MH16.1-2021 (RMI) with AISI S100-16 (with S2-20) for the members.
ANSI MH16.1-2021 is not in the library. Every MH16.1 provision in this calculation is written from knowledge and marked "to confirm against the code text"; every factor it sets is an input with its usual value prefilled. Read the Specification (free from MHI) before relying on the results.
Inputs of the storage rack #
- Rack: beam levels at a uniform spacing (the first level at the same height), the number of bays and the beam length, the frame depth and the bracing panel height.
- Loads: the product load per level per bay (all its pallets), the number of pallets (the unit load for impact), the rack's own dead load, impact on the beams as a fraction of one pallet (0.25 prefilled), and the product load factors for gravity (1.4 LRFD, 1.0 ASD prefilled) and with seismic (1.0 prefilled).
- Beams and connectors: the beam C-section, one C or two toe to toe as a box (closed by its connections, your confirmation), Fy, the connector's rotational stiffness F and its moment and shear strengths in the method's terms (all from the manufacturer's tests), the locking device's upward strength, and the deflection limit (L/180 prefilled).
- Upright frames: the upright C-section and Fy, the Q factor from the stub column test, the net-to-gross area and section modulus ratios for the perforations, Kx (1.7 down-aisle), Ky (1.0) and Kt (0.8) over the panel, Cm, and the bracing section and Fy.
- Seismic: SDS, Ip (1.0; 1.5 in areas open to the public), the product share of the seismic weight (0.67), Cs from SDS Ip / R or entered, R down-aisle (6.0) and cross-aisle (4.0), the height ratio of the first story's inflection point (0.5 prefilled, 0 for a pinned base: your call), and the product share that resists overturning.
- Base: the base plate's bearing area, the slab's f′c and the anchor's uplift strength.
Auto-design varies the beam, upright and bracing sections, lightest first. The geometry, loads, connector properties, the MH16.1 factors and the seismic inputs are kept.
Checks performed #
| Check | Basis |
|---|---|
| Beam flexure at midspan with the connector's end restraint, shear | S100 F2, F3, G2; MH16.1 (to confirm) |
| Beam deflection under the product load | MH16.1 L/180 (to confirm) |
| Connector moment (gravity with impact; gravity with down-aisle seismic), shear, locking device | MH16.1 connector tests (entered) |
| Upright compression with the Q factor | S100 E2; MH16.1 (to confirm) |
| Upright compression and down-aisle bending | S100 H1.2 |
| Frame bracing compression and tension | S100 E2, E3, D2 |
| Anchor uplift from cross-aisle overturning | Anchor strength (entered) |
| Base plate bearing | AISC 360-22 J8 |
The beam's end moment on springs F at both ends is Me = (w L²/12) / (1 + 2EI/(F L)); the midspan moment is w L²/8 − Me and the deflection subtracts the end moments' share. The seismic forces are the equivalent lateral force method: V = Cs W with Cs = SDS Ip / R (the short-period plateau, never less than 0.044 SDS Ip), distributed by w h. Down-aisle, the portal method gives the column shears (end columns V/(2 bays), inside columns twice that) with the inflection at mid-height above the first level; the connector moment at a level adds the column moments above and below the joint. Cross-aisle, the frame's diagonals take the story shear along their length.
Limitations #
- MH16.1-2021 provisions are from knowledge, to confirm. The Specification's other load cases (top level only loaded, partially loaded, the vertical impact of a dropped load on uprights, rack-supported structures) are not run.
- The portal method replaces a semi-rigid frame analysis; the first-story inflection ratio is your input. P-delta is the S100 H1.2 amplification only.
- The slab, the anchors' concrete strength, perforation patterns, the bolts of the bracing and row spacers are not designed.
Verification examples #
Verification status: 7 values compared in 1 example (0 published, 1 hand calculations from the cited equations): 7 within tolerance, 0 recorded deviations. No published example: every value is a hand calculation. That checks the program against this reading of the code, not the reading itself. Code basis: not yet recorded for this module.
No published rack design example is in the free library. The values are hand calculations of the spring-end beam moment, the seismic base shear and bracing force, the Q-factor effective area and the base bearing.